2.2. Demagnetization Measurements
To clean the secondary magnetizations from the sedimentary samples, we
applied a stepwise alternative field (AF) demagnetization method in
Pruhonice Paleomagnetism Laboratory of Czech Academy of Sciences. This
method was carried out using a 2G Enterprises Cryogenic Magnetometer on
44 samples divided into 3 different sequences. The first sequence was 17
samples (13_0P, 10_5P, 09_8P, 08_5P, 05_9P, 03_8P, 01_2P, 01_2M,
03_5M, 05_8M, 08_2M, 10_0M, 13_0M, 15_0M, 17_2M, 19_2M, 22_0M)
where we demagnetized at 1 mT intervals between 0-49 mT and 10 mT
intervals between 50-100 mT. The second sequence was 14 samples (12_0P,
07_1P, 04_2P, 01_5P, 01_0M, 02_7M, 05_6M, 08_0M, 10_5M, 12_7M,
15_4M, 17_9M, 20_1M, 22_5M) where we demagnetized at 2 mT intervals
between 0-48 mT and 10 mT intervals between 50-100 mT. The third
sequence was 13 samples (10_0P, 07_7M, 05_6P, 03_0P, 00_2P, 01_8M,
04_2M, 06_2M, 09_1M, 12_8M, 14_5M, 17_0M, 21_5M) and we
demagnetized at 0.5 mT intervals between 0-39.5 mT and 10 mT intervals
between 40-100 mT. Demagnetization data was interpreted by using
Remasoft software which was written by Agico Company (Chadima and
Hrouda, 2009).
Characteristic remanent magnetization (ChRM) directions and maximum
angular deviation (MAD) values were determined from principal component
analysis (PCA) (Kirschvink 1980) on Zijderveld diagram (Zijderveld,
1967). Virtual geomagnetic pole’s (VGP’s) latitudes and longtitudes were
calculated using PMGSC software by Randy Enkin. Table 1 shows the data
of alternative field demagnetization for each individual sample. Two
examples of alternative field demagnetization method for Matuyama and
Brunhes sections of the samples with changes of declination, inclination
angles and remanent magnetization intensity step by step are given in
Figure 4. Rest of the samples are in the supplementary table S1 and
table S2 containing supplementary Figures. Maximum angular deviation
(MAD) changes of this study and comparisons with previous studies (Okada
et al., 2017; Sagnotti et al., 2014) are shown in Figure 5.
Table 1: Alternative field demagnetization, virtual geomagnetic
pole (VGP) data and Matuyama-Brunhes magnetic reversal scale for this
study. Minus (-) values for virtual geomagnetic pole (VGP) latitudes and
longtitudes indicate southern and western hemisphere. MAD: maximum
angular deviation, φp: VGP latitude, λp:
VGP longtitude.